Yenisei Kirghiz

The Yenisei Kirghiz (539-1219) were a Turkic people that originated in the present-day Russian republic of Tuva, and in 840 they conquered the Uyghur Khaganate, reigning until 1219, when the Yenisei Kirghiz submitted peacefully to Genghis Khan.

History
The Yenisei Kirghiz were a tribe of Turks that came from the present-day republic of Tuva in Russia, just north of Mongolia. They settled to become a nation in 539 AD, and they expanded their nomadic state. In 840, they took over the Uyghur Khaganate after Khan Oge of Mongolia's death, but after the death of Khan Uzluk of Mongolia in 1040, Khan Zongzhen of Liao Kingdom took over the Yenisei Kirghiz, leaving a rump state as they seized most of what used to be their empire. The Kirghiz later submitted peacefully to the Mongol Empire in 1219, having outlasted the Liao, who split into more dynasties.